Part Weight Calculator from STEP
Upload your 3D model as a STEP file, pick the material, and get the part's weight, volume and dimensions instantly. The file is read in your browser and is not uploaded anywhere.
Prefer PREMSAProcessed in your browser
Part weight
Upload your STEP and get your part’s real weight
We measure the exact volume of the solid, holes, pockets and cutouts included. Pick the material and we give you the weight.
Drag your STEP file here · .step or .stp, up to 200 MB. The file is not uploaded.
Materials
Volume
—
Density
0.0975 lb/in³
Dimensions (length × width × height)
—
This is a very close estimate: the volume comes exactly from the model (under 0.1% error) and the density from the datasheet. Actual weight can vary by less than 1% in metals and about 2% in plastics depending on supplier, temper and grade.
Quote your CNC machined part
Upload your STEP here to get its weight; with the same file we give you a price and lead time instantly.
How it works
Weight is the volume of the solid in your STEP file times the material's density. Holes, pockets and cutouts are already taken out of that volume, so you don't enter any dimensions. One density is used for the whole file, so an assembly made of different materials will give the wrong weight.
How to use the calculator
- 1
Export the part from your CAD program as a STEP solid (AP214 or AP242). A surface-only model has no volume.
- 2
Drop the file in and pick the material. “PREMSA” lists the materials we machine, “All materials” has the rest, and in “Custom” you enter the density from your material certificate.
- 3
If the file contains several solids, each one is weighed and added up, including any screws, nuts or inserts in the export.
- 4
Compare the total with your CAD program. If it is thousands of times too large or too small, the STEP was exported in another unit (inches instead of millimeters).
Worked example
Aluminum plate with four holes
- Inputs
- A 100 × 60 × 10 mm plate with four Ø6.6 mm through holes, in 6061-T6 aluminum (2,700 kg/m³).
- Result
- Solid volume = 58.63 cm³ and weight = 158.3 g (0.349 lb).
- The block is 60.00 cm³ and each hole removes π × 3.3² × 10 = 342 mm³, or 1.37 cm³ for all four. 58.63 cm³ × 2.70 g/cm³ = 158.3 g.
Formula
m = V × ρ
Your browser reads the volume of each solid in the STEP file (V) and multiplies it by the density of the material you picked (ρ).
Assumptions and limits
- The file needs at least one closed solid. Surfaces and open shells have no volume.
- One density is applied to every solid in the file.
- Paint, anodizing, coatings and hardware that isn't modeled are not counted.
- Densities are nominal values for each alloy or resin. If you have the material certificate, use “Custom”.
Where the densities come from
Each density comes from the body that defines the alloy or the company that makes the resin, at 20 °C: the Aluminum Association, the ASM Handbook, the Copper Development Association and each plastic maker's datasheet.
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Questions about part weight
- How accurate is the weight from the calculator?
- The volume is taken from the STEP solid with under 0.1% error, compared against the model's exact volume. The density is the material's datasheet value. Actual weight is within 1% for metals and about 2% for plastics, because density varies slightly by supplier, temper and grade.
- Is my file uploaded to a server?
- No. The file is read inside your browser and never leaves your computer. It is only uploaded if you choose to quote the part and click “Get a quote online”.
- Which file formats are supported?
- STEP (.step or .stp), which every CAD program exports: SolidWorks, Inventor, Fusion 360, CATIA, NX, Creo and Onshape. The file must contain solids; a surface-only model has no volume.
- Does the weight include coatings or hardware?
- Only what is modeled. Paint, anodizing and coatings are not in the volume, and neither is hardware that isn't in the file. If the STEP does include screws or nuts, they are weighed with the same material you picked.
- Why does my CAD program show a different weight?
- Usually it's the density: your CAD program uses the material assigned in the file, while this calculator uses the one you pick here. Match the density first; if it still doesn't agree, check the unit the STEP was exported in and whether it contains extra solids.
- What if my file contains several parts?
- The calculator adds up the volume of every solid in the file and tells you how many it found. For the weight of a single part, export that part alone as STEP.
- What if my material isn't listed?
- Look in “All materials” first. If it isn't there, choose “Custom” and enter its density in kg/m³, g/cm³ or lb/in³; you'll find it on the supplier's datasheet or the material certificate.
- How do I convert kilograms to pounds?
- Multiply kilograms by 2.20462. The calculator already gives the weight in kg and lb, and the volume in cm³ and in³.
The volume is taken from the STEP solid with under 0.1% error, compared against the model's exact volume. The density is the material's datasheet value. Actual weight is within 1% for metals and about 2% for plastics, because density varies slightly by supplier, temper and grade.
No. The file is read inside your browser and never leaves your computer. It is only uploaded if you choose to quote the part and click “Get a quote online”.
STEP (.step or .stp), which every CAD program exports: SolidWorks, Inventor, Fusion 360, CATIA, NX, Creo and Onshape. The file must contain solids; a surface-only model has no volume.
Only what is modeled. Paint, anodizing and coatings are not in the volume, and neither is hardware that isn't in the file. If the STEP does include screws or nuts, they are weighed with the same material you picked.
Usually it's the density: your CAD program uses the material assigned in the file, while this calculator uses the one you pick here. Match the density first; if it still doesn't agree, check the unit the STEP was exported in and whether it contains extra solids.
The calculator adds up the volume of every solid in the file and tells you how many it found. For the weight of a single part, export that part alone as STEP.
Look in “All materials” first. If it isn't there, choose “Custom” and enter its density in kg/m³, g/cm³ or lb/in³; you'll find it on the supplier's datasheet or the material certificate.
Multiply kilograms by 2.20462. The calculator already gives the weight in kg and lb, and the volume in cm³ and in³.
Got a part in mind?
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